Arabis macdonaldiana (McDonald's rock-cress) 5-Year Review: Summary and Evaluation Arabis macdonaldiana: Red Mountain, Mendocino County, California Photograph used courtesy of David Imper U.S. Fish and Wildlife Service Arcata Fish and Wildlife Office Arcata, California May 2013 5-YEAR REV~EW Arahis macdonaldiana (McD nald's rock-cress) I. GENERAL INFORMATION Purpose of 5-Year Reviews: The U.S. Fish and Wildlife Service (Service) is requir d by section 4(c)(2) of the Endangered Species Act (ESA) to conduct a status review of each l ~ sted species at least once every 5 years. The purpose of a 5-year review is to evaluate whetherf:r not the species' status has changed since it was listed (or since the most recent 5-year revi w). Based on the 5-year review, we recommend whether the species should be removed fr m the list of endangered and threatened species, be changed in status from endangered to threa ened, or be changed in status from threatened to endangered. Our original listing of a spelies as endangered or threatened is based on the existence of threats attributable to one or more f the five threat factors described in section 4(a)(l) of the ESA, and we must consider thes same five factors in any subsequent consideration of reclassification or delisting of a speci s. In the 5-year review, we consider the best available scientific and commercial data on the sp cies, and focus on new information available since the species was listed or last reviewed. If we recommend a change in listing status based on the results of the 5-year review, we m t propose to do so through a separate rule-making process defined in the ESA that includes ublic review and comment. Species Overview: Arabis macdonaldiana (McDonald's rock-cress), a per nnial herbaceous member of the Brassicaceae (mustard family), was one of the first pl t species to be listed as endangered under the ESA. The species was listed in 1978. McDonald' rock-cress is characterized by lavender or crimson-purple flowers and a deep green rosette of bro dly spatulate (spoon-shaped) leaves from which the short flowering stems arise. It is particular! striking when observed amidst the often barren, steep, serpentine rock slopes on which it occur . The species is distinguished from other rock-cress species by its toothed, generally hairless ba al leaves (leaves at the base) less than one inch long. Arabis macdonaldiana occurs in soils deriv d from ultramafic parent material, containing high levels of heavy metals and low levels f nutrients. Its habitat ranges from barren gravel slopes to open scrub and pine woodlands. The ajority of the distribution occurs within a designated wilderness area. At the time it was listed, Arabis macdonaldiana was c nsidered to be restricted to a single population at Red Mountain, Mendocino County. Ho ever, in 1993, the taxonomic treatment of the species was revised to include populations of purpl -flowered rock-cress located near the Oregon border. Since 1993, the species was thought t occur in Mendocino, Del Norte, and the very western portion of Siskiyou counties in Californi , and the very southern portion of Curry County in Oregon. However, recent genetic work indi ates that Arabis macdonaldiana is confined to Red Mountain, Mendocino County, Califo ia (see the Taxonomy and Genetics section below). 2 Methodology Used to Complete the Review: This review was conducted by the Arcata Fish and Wildlife Office (AFWO) following March 2008 guidance issued by Region 8 of the Service. We used information from the Arabis macdonaldiana recovery plan (Service 1984), data/records contained in Service files, relevant information provided by other agencies and experts, and data from the California Natural Diversity Database (CNDDB) maintained by the California Department of Fish and Wildlife (CDFW). The recovery plan, information contained in Service files, and unpublished monitoring and research reports were the primary sources of information used to update the species' status and threats. This 5-year review contains updated information on the species' biology and threats, and an assessment of that information compared to that known at the time of listing. No other 5-year reviews have been conducted since listing. We focus on current threats to the species that are attributable to the ESA's five listing factors. The review synthesizes all this information to evaluate the listing status of the species and provide an indication of its progress towards recovery. Finally, based on this synthesis and the threats identified in the five­ factor analysis, conservation actions are recommended for future initiation within the next 5 years. Contact Information: Lead Regional Office: Larry Rabin, Deputy Division Chief for Listing, Recovery, and Environmental Contaminants; and Lisa Ellis, Fish and Wildlife Biologist, Region 8, California and Nevada; (916) 414-6464. Lead Field Office: Kathleen Brubaker, Arcata Fish and Wildlife Office; (707) 822- 7201. Federal Register (FR) Notice Citation Announcing Initiation of This Review: A notice announcing initiation of the 5-year review of this taxon and the opening of a 60-day period to receive information from the public was published in the Federal Register on March 25 , 2009 (74 Federal Register 12878). No comments were received in response to the notice. Listing History: Original Listing (Service 1978) FR Notice: 43 Federal Register 44810 Date of Final Listing Rule: September 28, 1978 Entity Listed: Arabis macdonaldiana (species) Classification: Endangered State Listing: Arabis macdonaldiana (McDonald's rock-cress) was listed by the State of California as endangered in 1979. Associated Rulemakings: None Review History: No status reviews or other documents that contain a five-factor analysis and conclusion have been conducted since the taxon was listed. 3 Species' Recovery Priority Number at Start of 5- ear Review: The recovery priority number for Arabis macdonaldiana is 14c according to the SeIWice's 2009 Recovery Data Call for the AFWO. Recovery priority numbers are based on a 1 18 ranking system, where 1 is the highest­ ranked recovery priority and 18 is the lowest (Endan ered and Threatened Species Listing and Recovery Priority Guidelines, 48 FR 43098, Septemb r 21, 1983). This number indicates that this taxon faces a low degree of threat, has a high pot ntial for recovery, and is in potential conflict with construction or development (surface m ning). Recovery Plan or Outline: Name of Plan or Outline: McDonald's Roe -cress Recovery Plan (Arabis macdonaldiana Eastwood) Date Issued: February 28, 1984 II. REVIEW ANALYSIS Application of the 1996 Distinct Population Segme t (DPS) Policy: The ESA defines "species" as including any subspeci s of fish or wildlife or plants, and any distinct population segment (DPS) of any species of ertebrate wildlife. This definition of species under the ESA limits listing of distinct popul tion segments to species of vertebrate fish or wildlife. Because the species under review is a pl t, the DPS policy is not applicable, and the application of the DPS policy to the species' listi g is not addressed further in this review. Information on the Species and its Status: In her original description of Arabis macdonaldiana ( cDonald's rock-cress), Alice Eastwood (1903) employed the spelling Arabis mcdonaldiana i honor of Captain James M. McDonald. Critchfield ( 1977) changed the spelling of the specifi~ epithet to "macdonaldiana," believing the original spelling to be in error. The original spelling 'mcdonaldiana" was used in the species recovery plan (Service 1984). However, to be consis ent with the original listing rule, the spelling "macdonaldiana" is used in this document. Species Biology and Life History: Arabis macdonaldiana is a showy perennial herb int e Brassicaceae (mustard family). The species was first discovered in northern Mendocino C unty, California in 1902, and described the following year by Alice Eastwood, a prominent e ly California botanist (Eastwood 1903). The species has a branched caudex (short, vertical, o en woody stem at or just beneath the ground surface) and several simple stems ranging fro 2 to 10 inches in height (Hickman 1993). The lower leaves are in rosettes (a cluster ofleaves in a circle), spatulate (rounded above and narrowed to the base), and range between 0.4 and 0.8 inch long and 0.2 to 0.3 inch wide. The leaves are toothed, and essentially smooth. Plants oft n do not flower and fruit every year. The petals are rose or purple in color and measure 0.35 to .43 inch long. Flowering typically occurs between April and May. As many as 12 siliques (elo gate fruits, dry, and open at maturity) up to 1.6 inches long may be produced, from which very small, slightly winged seed are 4 discharged. This species is distinguished from other rock-cress species by being almost glabrous (without hairs or glands) and having comparatively short, spatulate basal leaves. Arabis macdonaldiana is endemic (restricted to a well-defined condition) to serpentine soils. The term serpentine is used here in the vernacular sense, referring to soils derived from ultramafic parent materials that have been altered through a process called serpentinization. The factors accounting for serpentine endemism, and plant responses to serpentine soils have been well studied (Kruckeberg 1984). The major factor responsible for the restriction of certain plant species to serpentine soils seems to be the lower degree of inter-specific competition, compared to non-serpentine soils. Serpentine endemics have evolved means of coping with the harsh growing conditions presented by serpentine (e.g., low amounts of essential nutrients, especially calcium, and high concentrations of potentially toxic minerals such as nickel, chromium, and magnesium), while most other plant species are either unable to grow, or are less vigorous on serpentine.